Degrees of separation

Now that the school holidays are over, I've got back to my parents' archives, specifically today my father's. Here are my parents, in the middle part of this photo, at a dinner in the 50s, looking (well, being) very young. I remember that dress of my mum's. It was a sheer chiffon with fine black lines on it - giving the impression of being grey - and it had crimson and dark grey spots on it, with a black velvet ribbon in a bow at the front. 

My dad was a mathematician and engineer, a very clever chap, and he rose to be quite prominent in business. Here are six years' worth of group photos of a works dinner dance, all in the same room with an extraordinary ceiling. I have no idea where this was. 

The photographer seems to have been keener to feature the ceiling than the people. I think the heraldic bit is just painted on, so I imagine it no longer exists. 

Then I came across this letter to my father from Max Born, a well-known German physicist who won the Nobel Prize for his work on quantum mechanics. He was also my dad's professor at Edinburgh in my dad's later stint at university - after his war service. By this date, 1948, my father was working at Ferranti Ltd and was asked to give a talk, as above. I wonder what servomechanism theory is.

I idly Googled Max Born and found to my considerable surprise that one of his grandchildren is Olivia Newton-John.

Now when he was young, Mr L had a soft spot for ON-J - not that amazingly, given that she was very pretty and smiley. Today, he Googled her and discovered that she'd been born the day before Max B wrote the letter. 

Just think - my dad knew her grandpa, though I doubt whether my father had ever heard of O N-J. Still, that's 3 degrees of separation, isn't it? Mr L, my Dad, Max Born, O N-J. Or is that 4? - not sure how you calculate it. Anyway, considerably fewer than I'd have thought this morning. 

Oh, the throwing-out decisions, though... . What to keep, what to keep?